Multicellular organisms, including mammals, are made up of tissues, that is, organized aggregates of specialized groups of cells of similar form and function. In many tissue types, the cells are also surrounded by an extracellular matrix (ECM), a complex mixture of carbohydrates and proteins that provides support and anchorage for cells. When tissues become damaged, an ordered series of physiological events must take place in a timely fashion for successful tissue regeneration to occur. The first events, termed the inflammatory phase, include blood clotting as well as the arrival at the wound site of cells that remove bacteria, debris and damaged tissue. Later, circulating stem cells migrate to the wound site and differentiate into tissue-specific cell types. Finally, the differentiated cells begin to produce and deposit new ECM.
Successful repair of defective or damaged tissue depends in part on providing conditions that allow for appropriate cellular regeneration and that minimize the likelihood of infection during the repair process.